(1) Field of the Invention
This invention relates to a radiographic apparatuses such as an X-ray CT apparatus or MRI apparatus for use in thrusting a biopsy needle into a patient to remove a tissue from the patient for biopsy, or an injection needle into a patient to inject an anti-cancer drug or compound into a diseased part of the patient. More particularly, the invention relates to a technique of predicting a running path of a biopsy needle or injection needle (which may be called collectively hereinafter xe2x80x9cthrust needlexe2x80x9d).
(2) Description of the Related Art
In examining and treating cancer at medical institutions, a thrust needle is run into the patient""s body to remove a tissue for biopsy or inject an anti-cancer drug or compound into a diseased part. In one conventional method, for example, a thrust needle is run into the patient while monitoring running conditions of the needle by means of fluoroscopy provided by an X-ray CT apparatus. This practice will be described hereinafter, taking a biopsy needle for example.
In this method, as shown in FIG. 1, a fan beam FB is emitted from an X-ray tube (not shown) to a cross section (slice plane) D1 including a needle entry point A of a patient M lying on a top board 50. An X-ray detector (not shown) outputs X-ray detection data for providing a sectional image P1 of slice plane D1 which is displayed in real time on the screen of a display monitor 51 as shown in FIG. 2A, Then, a biopsy needle K is put to the needle entry point on the body of patient M. The operator, while looking at the screen of display monitor 51 to rely on what is seen thereon, gradually advances the biopsy needle K toward a tissue collection point B. At the same time, the top board 50 is moved for a fan beam FB to irradiate successively from the slice plane D1 including the needle entry point A to a slice plane Dn including the tissue collection point (goal) B.
As a result, different sectional images are successively displayed on the screen of display monitor 51. As shown in FIG. 2B, the point Ka of biopsy needle K appears with a sectional image Pm on the screen of display monitor 51. This enables the operator to continue advancing the biopsy needle K while constantly monitoring running conditions of the biopsy needle K on the screen of display monitor 51.
Finally, as shown in FIG. 2C, the point Ka of biopsy needle K reaches the tissue collection point B in a sectional image Pn of slice plane Dn of the patient M. Upon confirmation of this position of biopsy needle K, the needle running operation per se is completed.
However, where a conventional X-ray CT apparatus or the like is used in running a biopsy needle into a patient, it is difficult to secure an accurate running path of the biopsy needle. Moreover, the conventional practice of running the biopsy needle has a drawback of taking a very long time.
In running the biopsy needle K, the operator predicts a running path of biopsy needle K by observing only sectional images of slice planes of the patient M. It is difficult to predict a running path of biopsy needle K accurately by relying only on the sectional images of slice planes of the patient M. An inaccurate prediction of a running path of biopsy needle K will fail to secure an accurate running path of biopsy needle K.
In addition, between the needle entry point A and tissue collection point B, there may be vulnerable organs which must not be penetrated by the needle, or hard bones impenetrable by the needle. The operator has to run the biopsy needle K clear of such vulnerable organs and hard bones in a manner of trial and error relying on visual observation. This needle running operation consumes a long time.
This invention has been made having regard to the state of the art noted above, and its object is to provide a radiographic apparatus for enabling a thrust needle to be run through an accurate running path in an expeditious way.
The above object is fulfilled, according to this invention, by a radiographic apparatus for shifting slice planes imaged of a patient and displaying sectional images of the slice planes in real time on a display monitor in response to running of a thrust needle into the patient, in order to assist in running the thrust needle from a body surface of the patient to a target point in the patient, the apparatus comprising a screen input device for designating and inputting a needle entry point on the body surface of the patient and the target point in the patient, on a screen of a display monitor displaying the sectional images, and a guideline computing and displaying unit for computing a line segment linking the needle entry point and the target point, and displaying the line segment as a guideline superposed on the sectional images for guiding the thrust needle.
According to this invention, when running a thrust needle into a patient, sectional images including a needle input point on a body surface of the patient and a target point in the patient are displayed on the display monitor, and the screen input device is operated to designate and input the needle input point and target point on the screen. Then, the guideline computing and displaying unit immediately computes a line segment linking the needle input point and target point. The line segment computed is automatically displayed as a guideline superposed on the sectional images. Based on the guideline displayed as superposed on the sectional images on the screen of the display monitor, the operator may immediately determine whether a needle running path is appropriate or not. When the running path is found appropriate, the operator has only to run the thrust needle along the guideline. That is, with the apparatus according to this invention, the guideline serves as a reference for running the thrust needle, whereby a needle running operation may be carried out accurately and quickly. When the running path is found inappropriate, a needle entry point or a target point is designated all over again to compute and display a new guideline.
Preferably, the radiographic apparatus according to this invention further comprises an intersection computing and displaying unit for successively computing intersections of the slice planes and the guideline in response to shifting of the slice planes, and displaying intersection marks indicative of the intersections as superposed on the sectional images. When the thrust needle correctly runs along the guideline, the needle point never fails to meet the intersections computed. Thus, the operator has only to run the thrust needle in a way that the needle point coincides with the intersection marks representing the intersections computed. That is, the intersection marks representing the intersections serve as a reference for guiding the needle point to an exact position, whereby a needle running operation may be carried out accurately and quickly.
Preferably, the radiographic apparatus according to this invention further comprises a slice width range computing and displaying unit for successively computing slice width ranges each extending between opposite ends of a portion of the guideline present within a slice thickness across each of the slice planes in response to shifting of the slice planes, and displaying the slice width ranges of the guideline as superposed on the sectional images. With this construction, the operator runs the thrust needle to move the needle point precisely from the starting end to the finishing end of each slice width range of the guideline. That is, each sectional image on which the guideline is superposed includes data within its slice thickness combined and, so to speak, compressed thereinto. The thrust needle, strictly speaking, is run along the guideline just by an amount equal to the slice thickness. Thus, when the operator correctly runs the thrust needle based on each sectional image, the needle point moves precisely from the starting end to the finishing end of each slice width range of the guideline. Thus, the slice width range of the guideline superposed on each sectional image serves as a reference for guiding the needle point throughout the slice thickness to an exact position.